Assign a static drive letter

Is it at all possible to assign a constant letter to a drive that will say the same between computers? If not, is there a command line I can run as a .bat file that will set it without having to know the drive letter and manually set it?

The best way is to map a drive to a share and run it on either computer e.g.

@echo off
Net use H: \\computername\sharename /persistent:no

The persistent bit allows the drive letter to be removed when the user logs out and then re-apply when the user logs in again. You can put the script in the startup folder in the user's profile e.g.
C:\Users\username\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup

But what if I want to plug it into a computer that isn't part of my network?

Follow up question: is there any way to make the path locally hosted to the drive specifically instead of going through the drive letter? Just make it a self contained system. Are there any programs that can help short of drive manager?